Nine Japanese nationals have joined Islamic State, Japan's former air force chief, Toshio Tamogami, quoted a senior Israeli government official as saying, but the government's top spokesman said on Friday it had not confirmed the information.
Meanwhile, a senior US military commander said that around 1,000 recruits from the vast region stretching from India to the Pacific may have joined Islamic State to fight in Syria or Iraq.
Tamogami, Japan's former air force chief, now a senior official of a tiny new political party, said on his blog that Nissim Ben Shitrit, the director-general of Israel's foreign ministry, told him this month that nine Japanese had taken part in Islamic State.
Asked about the possible participation of Japanese citizens in the militant group, Chief Cabinet Secretary Yoshihide Suga told a regular news conference, "The government has not confirmed such information."
No one was immediately available for comment at the Israeli embassy in Tokyo, at the Israeli foreign ministry or at the Japanese foreign ministry.
Tamogami told Reuters that no details besides the number of Japanese participants were given to him in his meeting with Nissim Ben Shitrit, a former ambassador to Japan.
"I don't know anything further," Tamogami said. "He was tight-lipped." Tamogami's blog shows the meeting took place on Sept. 12 in Israel.
About 1,000 recruits from a vast region stretching from India to the Pacific may have joined Islamic State to fight in Syria or Iraq, the head of the US Armed Forces' Pacific Command, Admiral Samuel Locklear, said on Thursday.
His comment came as a threat by Philippine militants to kill a German hostage, in a show of solidarity with Islamic State, has stoked fresh concern the Middle East group's brand of radicalism is winning recruits in Asia and posing a growing security risk in the region.
"That number could get larger as we go forward," Navy Admiral Samuel Locklear, who heads the US Armed Forces' Pacific Command, told reporters at the Pentagon.
However, Locklear did not specify which of the 36 countries in the Pacific Command - some of which have their own Islamist movements - have been recruiting grounds for the Sunni fundamentalist militant group.
In addition to India, the Hawaii-based Pacific Command's area of responsibility includes Australia, China and other Pacific Ocean states. The command does not cover Pakistan.
Locklear told reporters that current estimates put at 1,000 the number of "potential aspiring fighters" that have moved from the region encompassed by the Hawaii-based Pacific Command. He did not specify a time period.
His comments came as a threat by Philippine militants to kill a German hostage in a show of solidarity with Islamic State has stoked fresh concerns that the Middle East group's brand of radicalism is winning recruits in Asia and posing a growing security risk in the region.
In the region, thousands have sworn oaths of loyalty to Islamic State as local militant groups capitalize on a brand that has been fueled by violent online videos and calls to action through social media, security analysts say.
Locklear said Islamic State recruitment was "high on the list" as officials look to future security concerns in Asia. He said most of the aspiring fighters had been recruited via social media and warned that officials were looking at ways to guard against blowback from potential attacks as foreign fighters return to their home countries.
"We are working with all of our partners and allies to see how we harden (security in) our own countries and the region and the world against a threat like (the Islamic State)," he said.
On Wednesday, the United Nations Security Council demanded that all countries make it a serious criminal offense for their citizens to travel abroad to fight with militant groups, or to recruit and fund others to do so.
On the same day, the United States designated two dozen individuals and groups as foreign terrorists or terrorist facilitators, enabling it to freeze assets and block financial transactions as it stepped up its offensive against Islamist militants in Syria, including Islamic State.